Contactless smart cards or hybrid contact-contactless smart cards are equipped mainly with an antenna embedded in the card and an electronic module connected to the antenna. These cards allow the exchange of information with the outside by remote, and therefore contactless, electromagnetic coupling, between their antenna and a second antenna located in the associated reader. In the case of a hybrid card, this exchange may also be done by electrical transmission of data between the flush contacts of the card's electronic module and the contacts of a reader's reading head into which the card is inserted. These cards are now used in many sectors. In this manner, in the transport sector, they are used as a means of access to the transport network. This is also the case for bank cards. Hybrid or contactless cards are used in all types of debit/credit account operations, a recent example being the electronic wallet. Many companies have also developed identification means for their personnel using contactless smart cards.
The electronic module inserted into the hybrid contact-contactless or contactless smart card is used for developing, storing and processing the information. The connection of the electronic module and the antenna is one of the significant manufacturing problems for smart cards. The dimensions required by the usual standards for smart cards makes their manufacture that much more tricky when an electronic module and an antenna connected together have to be inserted.
The manufacture of antennae by a screen-printing method using conductive ink has allowed the manufacturing constraints to be considerably reduced. Several antennae are screen printed at a time by one or more deposits of conductive ink such as silver and this makes this first step of manufacturing hybrid or contactless smart cards much faster and less expensive than methods used previously. Furthermore, the manufacturing of a screen printed antenna enables a very great adherence to be obtained for the antenna on its thermoplastic support and thus partly overcome the problem of detection of the antenna contacts during the connection step of the module and the antenna in the case of hybrid smart cards.
Unfortunately, the drawbacks of this type of antenna appear during the second manufacturing step of the card, which consists in laminating the various layers with plastic material that make up the card on either side of the antenna support. As the material flow is significant during the lamination step as a result of the high pressure and temperature, the antenna's shape factor is not maintained. The conductive ink forming the antenna contains only 15% of binder, which results in a mechanical strength that is insufficient in temperature and pressure conditions of the order of 180° C. and 280 bar. As a result, there appear variations in the electrical parameters (inductance and resistance) of the antenna and this results in malfunctions. In addition, it is not uncommon to experience antenna breakage in areas where strong shear stresses are present. This is particularly the case in corners and at electrical bridges.
The document WO 01/95252 describes a contactless smart card including an antenna on a support, and the antenna may be made by printing using conductive ink. The invention described particularly concerns a strip of smart cards consisting of a support strip (1) whose softening temperature is at least 110° C., preferably 180° C., and a cover strip whose softening temperature is not greater than 110° C. It also concerns a method used to manufacture this smart card strip. This method consists in manufacturing this smart card strip in the form of a continuous strip made up of a support strip and a cover strip fixed to one another.
The document EP 1 189 168 also describes a contactless smart card including an antenna on a support, the antenna and the chip being supported by biodegradable material.